In recent years, there has been a demand for environmentally friendly pneumatic tires to suppress worsening of the global environment. Therefore, it is necessary to reduce the rolling resistance of tires and to enhance the fuel economy performance. Furthermore, the pneumatic tire for all seasons requires performance on snow during traveling on a snow-covered road and excellent wet performance and wear resistance during travelling on a non-snow-covered road (wet road surface and dry road surface).
Examples of known techniques of reducing rolling resistance include reducing a compounded amount of carbon black in a rubber composition constituting a tire and using a polymer having a low glass transition temperature as a polymer. Such a rubber composition can achieve the effect of reducing rolling resistance; however, grip performance, especially wet grip performance, which is an important basic property of tires, tends to be reduced.
International Patent Publication No. WO 2015/093316 proposes to enhance fuel economy performance, wet grip performance, and wear resistance by a rubber composition for a tire, the rubber composition including a butadiene rubber, an emulsion-polymerized styrene-butadiene rubber having a bonded styrene content of 35 wt. % or greater, and an aromatic modified terpene resin. However, this rubber composition for a tire exhibits insufficient performance on snow during traveling on a snow-covered road, and improvement in processability of the rubber composition has been also demanded.